net: openvswitch: silence suspicious RCU usage warning

ovs_flow_tbl_destroy always is called from RCU callback
or error path. It is no need to check if rcu_read_lock
or lockdep_ovsl_is_held was held.

ovs_dp_cmd_fill_info always is called with ovs_mutex,
So use the rcu_dereference_ovsl instead of rcu_dereference
in ovs_flow_tbl_masks_cache_size.

Fixes: 9bf24f59 ("net: openvswitch: make masks cache size configurable")
Cc: Eelco Chaudron <echaudro@redhat.com>
Reported-by: syzbot+c0eb9e7cdde04e4eb4be@syzkaller.appspotmail.com
Reported-by: syzbot+f612c02823acb02ff9bc@syzkaller.appspotmail.com
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/openvswitch/flow_table.c

@@ -518,8 +518,8 @@ void ovs_flow_tbl_destroy(struct flow_table *table)
 {
 	struct table_instance *ti = rcu_dereference_raw(table->ti);
 	struct table_instance *ufid_ti = rcu_dereference_raw(table->ufid_ti);
-	struct mask_cache *mc = rcu_dereference(table->mask_cache);
-	struct mask_array *ma = rcu_dereference_ovsl(table->mask_array);
+	struct mask_cache *mc = rcu_dereference_raw(table->mask_cache);
+	struct mask_array *ma = rcu_dereference_raw(table->mask_array);
 
 	call_rcu(&mc->rcu, mask_cache_rcu_cb);
 	call_rcu(&ma->rcu, mask_array_rcu_cb);
@@ -937,7 +937,7 @@ int ovs_flow_tbl_num_masks(const struct flow_table *table)
 
 u32 ovs_flow_tbl_masks_cache_size(const struct flow_table *table)
 {
-	struct mask_cache *mc = rcu_dereference(table->mask_cache);
+	struct mask_cache *mc = rcu_dereference_ovsl(table->mask_cache);
 
 	return READ_ONCE(mc->cache_size);
 }